1. Technical Field
The present invention relates to a circuit board suited for use in electro-optic devices, such as electrophoretic devices and liquid crystal devices, and other devices, an electro-optic device including the circuit board, and an electronic apparatus including the circuit board or the electro-optic device.
2. Related Art
An electro-optic device, such as a liquid crystal device and an electrophoretic device used for display applications and the like, or a detecting device such as a fingerprint sensor includes a circuit board (active matrix substrate) that has a plurality of electrodes arranged in a two-dimensional pattern and a plurality of transistors corresponding to the respective electrodes. A typical procedure for manufacturing such a circuit board is as follows. First, a plurality of transistors are formed on a substrate, and then an insulating film (insulating layer) is formed on the transistors. Contact holes (through holes or via holes) are respectively formed at a plurality of positions of the insulating film. Then electrodes that connect to the transistors through these contact holes are formed. Subsequently, in the case of making an electrophoretic device, an electrophoretic sheet is disposed on the circuit board to make an electrophoretic device. The same procedure applies to other devices.
In the related circuit board described above, electrodes and contact holes are provided on a one-to-one correspondence (refer to Japanese Unexamined Patent Application Publication Nos. 2004-288881 and 2007-103584). Accordingly, in order to decrease the electrode-to-electrode distance among the plurality of electrodes, very small contact holes must be formed. Formation of small contact holes requires high alignment accuracy and thus the yield is low.